Scroll images in project issues separately from the remaining issue (#31683)

As discussed in #31667 & #26561, when a card on a Project contains
images, they can overflow the card on its containing column. This aims
to fix this issue via snapping scrollbars.

---
Issue #31667 is open to discussion as there should be room for
improvement.

web_src/css/repo/issue-card.css

@@ -2,7 +2,7 @@
   display: flex;
   flex-direction: column;
   gap: 4px;
-  align-items: start;
+  align-items: stretch;
   border-radius: var(--border-radius);
   padding: 8px 10px;
   border: 1px solid var(--color-secondary);